The present invention relates to sensors for detecting the flow rate or pressure in chemical plants, iron mills and power plants, and in particular to highly reliable semiconductor composite sensors which continue to have high accuracy even if they are used for a long period of time.
As pressure sensors using the piezoresistance effect of silicon, various techniques have been proposed heretofore.
For example, two piezoresistive elements formed in the same n-type semiconductor region subjected to p-n separation are known as described in "Miniature Piezoresistive Strain and Pressure Sensors with On-Chip Circuitry," by Susumu Sugiyama et al., PROCEEDINGS OF THE 3RD SENSOR SYMPOSIUM (1983).
As another example of a conventional technique, a similar structure is disclosed in JP-A-3-76139 (UM) as well. Furthermore, a semiconductor pressure sensor based upon the piezoresistance effect is disclosed in JP-B-60-32993 as well, which corresponds to U.S. patent application Ser. No. 619,866 filed on Oct. 6, 1975.